PayPal, one of the largest fintech and online payment system leaders, uses Node JS in production almost since the very start. The fact is that they were using Java for the backend at first (just like Netflix did), but then PayPay adopted Node JS for their backend.
LinkedIn has over 60 million unique users using their mobile applications. To perform at such a scale the company needed a performing technological solution. LinkedIn used Rails for its mobile site, but it was too slow and poorly scalable. LinkedIn switched to NodeJS to solve its scaling problems. The company appreciated two advantages: the scale and the way Node communicates with its platform API and database.
Instagram has entirely used the ReactJS library. A vast number of its features, such as far loading, Geolocations, Google MAPs, image, and video delivery, and uploading, etc. are implemented due to ReactJS.
It based its tech stack on Java, but a few years ago, they switched to NodeJS to handle an issue with a specific service that Java could not handle. So they migrated their entire user face stack to NodeJS. Moving to Node.js was a big time saver for the global marketplace, its developers say.